Ag isotopic and chalcophile element evolution of the terrestrial and martian mantles during accretion: New constraints from Bi and Ag metal-silicate partitioning

Chromium on Mercury: New Results From the MESSENGER X‐Ray Spectrometer and Implications for the Innermost Planet's Geochemical Evolution

“…The pressure term is found to be insignificant (p-value higher than 10%). In addition, 𝐴𝐴 𝐴𝐴 met∕sil Cr becomes more siderophile with increasing temperature (Figure 6b), as previously reported (e.g., Fischer et al, 2015;Righter et al, 2020) and with increasing abundances of Si, S, C, and O in the metal. The nbo/t ratio has a negative effect on Cr partitioning between metal and silicate (Table 1).…”

The Lithophile Element Budget of Earth's Core

“…This result suggests that core formation plays a very minor role in the S depletion in Earth's mantle and rather the lack of S within Earth's mantle is due to volatilization during accretion of the planet or a S-poor source material. An important caveat, however, is that our parameterization does not account for silicate-sulfide or metal-sulfide partitioning of S. It is possible that sulfur was segregated out of the mantle as a sulfide, rather than a metal (e.g., the "Hadean matte" [Ballhaus et al, 2017;Laurenz et al, 2016;O'Neill, 1991;Righter et al, 2018Righter et al, , 2020Rubie et al, 2016]).…”

Cadmium isotope fractionation during metal-silicate partitioning – Results and implications for Earth's volatile accretion

“…These findings are in accord with classical models of accretion, which suggest that the majority of Earth's volatiles were added during main stage growth whilst core formation was still active and in line with observations that siderophile volatile elements are depleted in the BSE relative to lithophile elements of similar volatility because the former were additionally depleted by partitioning into Earth's core (Wood et al, 2010). Whilst metal-silicate partitioning of Cd appears to be largely independent of temperature and pressure, the partitioning data for other elements, as well as isotope and trace element studies, argue for heterogeneous accretion, whereby volatiles were primarily added during the last 10-20% of Earth's main accretion phase, most likely through addition of volatile-rich carbonaceous matter (Schönbächler et al, 2010;Wade et al, 2012;Mahan et al, 2018;Braukmüller et al, 2019;Budde et al, 2019;Righter et al, 2020;Kubik et al, 2021). The evidence available from most abundance and isotope studies of HSE and strongly siderophile volatile elements (particularly Se, Te) furthermore indicates that a small late veneer of <1% M E and with a composition akin to CI or CM chondrites was added to Earth after completion of core formation.…”

“…This 'classical' model of volatile accretion predicts that most of Earth's volatile elements were acquired during main stage accretion whilst core formation was ongoing. In this case volatile addition may have occurred either throughout Earth's formation or, according to heterogeneous accretion models, primarily during the late stages of the main accretion process, when Earth assimilated volatile-rich carbonaceous planetesimals (e.g., Schönbächler et al, 2010;Wade et al, 2012;Braukmüller et al, 2019;Budde et al, 2019;Righter et al, 2020;Kubik et al, 2021). In this case, the late veneer only dominates the mantle abundances of the most siderophile elements.…”